A slave that runs away is a Kufr

حَدَّثَنَا عَلِيُّ بْنُ حُجْرٍ السَّعْدِيُّ، حَدَّثَنَا إِسْمَاعِيلُ، - يَعْنِي ابْنَ عُلَيَّةَ - عَنْ مَنْصُورِ بْنِ عَبْدِ الرَّحْمَنِ، عَنِ الشَّعْبِيِّ، عَنْ جَرِيرٍ، أَنَّهُ سَمِعَهُ يَقُولُ ‏ "‏ أَيُّمَا عَبْدٍ أَبَقَ مِنْ مَوَالِيهِ فَقَدْ كَفَرَ حَتَّى يَرْجِعَ إِلَيْهِمْ ‏"‏ ‏.‏ قَالَ مَنْصُورٌ قَدْ وَاللَّهِ رُوِيَ عَنِ النَّبِيِّ صلى الله عليه وسلم وَلَكِنِّي أَكْرَهُ أَنْ يُرْوَى عَنِّي هَا هُنَا بِالْبَصْرَةِ ‏.‏

It is narrated on the authority of Jarir that he heard (the Holy Prophet) saying, "Any slave who fled from his master is guilty of Kufr, until he goes back to them." Mansur observed: By God, this hadith was narrated from the Apostle (may peace and blessings be upon him), but I do not like that this should be narrated on my authority here in Basra.

Sahih Muslim 68 https://sunnah.com/muslim:68

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حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، أَخْبَرَنَا جَرِيرٌ، عَنْ مُغِيرَةَ، عَنِ الشَّعْبِيِّ، قَالَ كَانَ جَرِيرُ بْنُ عَبْدِ اللَّهِ يُحَدِّثُ عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ "‏ إِذَا أَبَقَ الْعَبْدُ لَمْ تُقْبَلْ لَهُ صَلاَةٌ ‏"‏ ‏.‏

Jarir b. Abdullah reported it from the Holy Prophet: When the slave runs away from his master, his Salat is not accepted.

Sahih Muslim 70 https://sunnah.com/muslim:70